TEMPORAL TRENDS OF HYDROCLIMATIC VARIABILITY IN THE LOWER BUZĂU CATCHMENT

Iulian MITOF, Remus PRĂVĂLIE

ABSTRACT: This paper examines the temporal trends of climatic water balance value and streamflow rate variability in the lower catchment of the Buzău River, as well as the statistical relationship between the two variables over the past five decades. The analysis is based on a series of climatic data provided by the Buzău and Brăila weather stations, and on hydrological data on the average streamflow rates of the Buzău River, between 1960 and 2009. Thus, the first phase aimed to quantify detailed annual, seasonal and monthly climatic and hydrological trends, using the non-parametric Mann-Kendall test. In the second phase, in order to describe the relationship between the independent variable (climatic factor) and the dependent one (average streamflow), statistical correlations between the two sets of data were analysed on the three temporal scales, and the statistical significance of the r correlation coefficient was identified with the Bravais-Pearson test. The results showed that, in terms of climate, the trends point to interannual and seasonal humidity deficit rises, except for the fall season, which generally shows a deficit decrease, due to higher average precipitation values. The situation is similar in the case of hydrological trends, characterized by interannual and seasonal streamflow values decreases, except for the fall season again, as a consequence of climatic trends. The correlations between the two variables proved the statistical relationship between the climatic and hydrological variabilities, with lower seasonal (winter) r correlation coefficient values, due to the solid precipitation that does not directly supply the Buzău River.

Keywords: Buzău catchment, climatic water balance, streamflow, variability, trend analysis.

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